Protected grate



Feb. 19, 1935. J MOORE 1,991,815

PROTECTED GRATE Filed Sept. 25, 1931 2 Sheets-Sheet l Feb 19, 1935. MOORE 1,991,815

PROTECTED GRAT-E Filed Sept. 25, 1951 2 Sheets-Shet 2 Fig.6.

Patented Feb. 19, 1935 w 1,991,815

, UNITED T T-Es PATENT OFFICE G. Remmey Son C0,, Philadelphia, 2a., a corporation of Pennsylvania Application September 23,1931, Serial No; 564,534 16 Claims. (Cl.'11033) This invention relates to furnace grates and replacement may be thereupon conveniently comprises (a novel grate having its supporting ,or reached. 3 fuel-bed face protected by replaceable block units As herein sho n, I have arranged the refracof refractory material. V v tory Jolock units at transverse rows and in over- It is well recognized that am'etallic furnace lapping relation. This is not only important grates, and particularly those employed under in securing the individual units in place upon the boilers in industrial installations, are subjected crate, bu by p per sha in th uni ran to destructive temperature conditions which verse channels or grooves maybe provided in iortens the life of the grate and impair its thefface of the grate which serve to retain the 1'0 mechanical .efl'iciency. The defects due to warpfuel against slipping downwardly the grate. 1Q

ingand cracking of metallic grate bars are par- Another important feature uof m invention ticularly objectionable in .movable grates emconsists in a protected grate having air passages ploy'eo. in. connection with mechanical stokers therein by which air is admitted through-the fuel since any distortion of the grate bars is likely bedand-the efficiency of combustion therebyzi nto interfere with therequired movement of the proved. In the construction herein shown, the grate or the stoker parts. supporting frame of the grate is provided with I have discovered that the diificulties heretoair passages and the refractory block units of for-eencountered may :be largely .elirninatedand the facing are also provided withair passages the life of the grate increased to a striking deand areassernhled upon h Irame o that their gree by protecting its fuel-bed face with a facair passages substantially register with those of 89 nc of refra ory cerami block o bl ck unit the ram assembled in transverse rows, the units in each It is important that the air passages be'of row over-lapping jthOSB in the next lower row sufficient size to result in acooling action upon andthus serving to hold them in place upon the the refractory facing andadmit sufficient air bed of the.-grate. V forcombustionand still besmall-enough in area 2;

lit is important to secure the refractory block to prevent clinkers from working into them. As unitsgdetachably but reliably in place in assemherein sh wn, these desirable objects are accombling the facing and positively to preventtheir plished by a novel arrangement of air passages displacement when the grate isnioved on-when or ports in the individual block units. These are fuel delivered thereto. These objects Iatarranged 'in relatively offset or displaced relation 3p tain zby providingan interlocking connection;besp thatwhen the units are assembled, the ports tween the individual block units and the sup in adjacent ends thereof do not symmetrically portingface of the grate frame, whichisdesigned register at the fuel .bed face of the units. The to retain the units against separation from the staggered relation of the ports thus presents no supporting face and at the same time permit" 1 1 1115 o substantial Width a ou h he agthem to be moved parallel thereto "into or'out gregate ar 9 't S m um i of any selected'position while .so retained. h sg eme t fi h gl' fi 'u .all.working "It is-irnportant also Ithat the refractory block Q -i units be so-assembled in the grate that any sees dm r e :alspect, lm mi n q mlected unit may be removed for repair orrepnses'a Protected grate provided wlth 49 having staggered or offset openings- In another aspect, .it consists in a refractory block unito'f novel rforxn adapted for use in a protective facing of the character described. An important feature of-such a block unit consists in airports placement andfor this purpose bolts and cla'mping fasteners in general have been found unsatisfactorybecause of the effect thereon of the 45 heat'to which they are subjected in-use. With a Overcoming; this dlfficuniy my "mvientwn extendingfromits-upperandlower face in oppocontempla'tes a 'facmg refractory lblorck'rumts site sides thereof which ports are .unsymme'tri- Whichmay b retained in operatiVeIpositiQn lip-Cm call-y arranged so that adjacent units maybe the grate by aholdl'd-own member of Simple assembled yvith theports-in ofiset relation. An-

50 struction but which is effective y reason its other feature of the novel block unit herein-shown 50 1 39 a e t i v n nsdi p a ement 1' consists in 'the construction which includes .an Q KJl i fi ase ql qomp s t I in'eunder cut face (at one edge of the unit and" a v By -removing the holdedovvn-mcrnber, 'anyllongi beveled face at the other edge of the nnit, the tudinaltieror row of block-units .is made accesffaces being-sodesigned and-proportioned thatthe 50 sinleensi th indivi ua u th r n se ct p o ber fiec o o a n mayib p ela pineanp l interlocked with the under-cut face of the next adjacent unit.

Still a further feature of the invention consists in a novel form of a refractory block unit having a curved face and being adapted for use in the lower tier or row in the grate. As herein shown, these units are arranged to retain in position the higher block units-of the protectivefacing of the grate and are themselves retained in place by being over-lapped. For this purpose the unit is provided with a portion bounded by flat faces for interlocking engagement with an overlying block unit, and with channels or grooves in its inner face for receiving correspondingly located tangular in its general contour and increases in thickness from one edge to the other. ner edge of the unit is provided with an inclined retaining bars or flanges.

These and other features of the invention will be. best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration; and shown in the accompanying drawings, in which,

Fig. 1 is a view in perspective of one section of a protected grate with parts broken away and certain ofthe block unitsremoved. 1

Fig. 2 is a View in-perspective, on an enlarged scale, of one of the block units of the protective facing.

Fig. 3 is a similar view showing the unit in different position.

Fig. 4 is a similar view of one of the block units of the lowermost tier. V

Fig. 5 is a view in end elevation, on an enlarged scale, of the hold-down member and adjacent parts, and V Fig. 6 is a view in down member.

As herein shown, my invention is embodied in one section of a reciprocating extension grate for an underfed stoke'r fired boiler. This represents one of the most advantageous applications of my invention, but it will be understood that it is not by any means limited to this or to any other specific type of grate or installation.

The metallic frame of the grate includes side pieces 10 of triangular contour and an inclined bed piece 12, together-with a lower cross-bar 18 and an upper cross-bar26. The inclined bed piece 12 is provided at regular intervals across its face with longitudinal undercut or dove-tailed ribs 1e and suitably spaced between the ribs 14 are air passages 16 which extend through the bed piece and serve to admit air through the fuel bed.

At the lower forward edge'of the grate frame is provided the lower cross-bar 18 and this is formed With an upstanding flange at its forward edge and with a series of short transverse ribs 20 on its upper face. The lower cross-bar also includes a vertical flange 22 standing higher than the edge flange and provided with a series of square notches 24 in its upper edge which constitute air passages corresponding to the passages 16 of the bed piece 12.

At the upper rear end of the grate is provided the upper cross-bar 26 and this is similarly provided with notches 28 in its upper edge. An elongated hold-down member 30 which may be either of cast iron or refractory material, is de-' signed to fit with the upper crossbar 26 and for this purpose is provided with spaced ribs 33 and 35 upon its lower face which form between them front elevation of the holda channel of the proper dimensions to receive the cross-bar 26. The hold-down member 30 may extend from one side to the other of the grate as an integral piece or in sections and by resting upon the uppermost row'of block units holds the entire assembly in place. The under side of the upper or web portion of the hold-down member is provided with air passages 31. Elongated lugs 32 are secured to the outer face of each side piece 10 for the purpose of spacing the grate sections and preventing rubbing of the block units of one section upon those of the next or upon the adjacent main castings of the grate. 7

I will now proceed to describe the individual block units of the facing and then the manner in which they are assembled in the grate. The block ,units are preferably of silicon carbide or other suitable refractory material which may be shaped and fired as is the practice in the manufacture of ceramic articles. Each block unit 40 is rec- The thinor beveled upper surface 42, the angle of bevel being relatively acute, for example 10, with the plane bottom face of the unit. The thicker edge of the unit is undercut to form a concealed block receiving space bounded by-a face 46 which is disposed substantially at right angles to its bottom face. Above the undercut edge face of the unit is a beveled upper face 44 oppositely inclined, as compared to the face 42 and at a more abrupt angle or inclination, for example 40. The intermediate portion of the upper face of the unit is inclined toward the thinner edge thereof as already indicated. Symmetrically disposed in the lower face of the block unit is a transversely extending groove or channel 48 with undercut side walls adapted to fit the dove-tailed ribs 14 of the. bed piece of the grate.

In each end face of theunit are provided air ports which merge into a single passage opening through the bottom face of the unit but which are dissimilar in their contour above the bottom face, as seen in Figs. 1 and 2. The left-hand face of the block unit is provided with three semi circular grooves which diverge and open through the upper surface of the unit in three semi-circular openings. The right-hand end face of the block unit, as best shown in Fig. 3, is provided with two semi-circular grooves which extend upwardly in substantially parallel relation and are thus arranged in offset or staggered relation with the diverging openingsin the left-hand end of the unit. In other words, the intermediate partitions between the three grooves 4'7 are located, in the assembled facing, opposite to the grooves 45 of the next adjacent unit. The opening of each port in the surface of the facing is thus of irregular contour, of substantial area in the aggregate, but nowhere sufficiently wide to admit a clinker.

The intermediate block units 40 of the facing are grooved at both ends as already described. The block units 41 for the outer longitudinal rows areeach grooved only at one endandare provided with plane outer end surfaces.

The block units 50 and 51 of the lowermost row are also rectangular in their generalcontour and each has an outer cylindrical face which merges at the upper edge of the unitinto a narrow fiat face 52 designed to fit the undercut orlower edge face of the block units 40'and 41 in the next higher transverse row. As in the fiat units, the units 50 are thicker at their lower edge than, at their higher edge. The inner face of each unit is irregular in outline being provided with a lower step in which is formed a longitudinal groove or channel 56, and with a higher step in which is formed a parallel channel 58. The channel 56 is designed to fit upon-the upstanding edge flange of tlie lower: cross-bar l8 and a channel 58 is designed to fltupon the higher flange 22. Both channels 56 and 58 extend verticallyin the block unit and in parallel v relation so that the unit may be placed uponor removed from the two flanges in-a verticalldirection but is held positively in positionagainst the-forward and downward pressurezofithehigher block units.. The short'ribs are spaced so that they engage the end faces of'the units, and'the end faces are notched to receive :them andthus positively preventtransverse displacement thereof upon the upstanding flanges. T r

' Each of the block units 50 is provided with air passages: in its. opposite end faces and, as in the flat units these open through the curved faces ofithe units in staggered or offset relation. As shown inFig. 4, the two passages 57 extend in a radial direction from a common opening in the inner face of. the unit to spaced semicircular openings. in its outer curved face. Similar passages 55are formed in the other face of the unit. 'I'heendiunit'fil'of the lowermost row is provided withairpassages in one end face and has a plain outer face. When the units 50 and 51 are assembled thezpassages in the adjacent ends form air. portsaofrirregular contour which communicate with the notches 24 inthe-flangeof the crossbar.l8;-. J.

In assembling the protective facing of the grate the. unitsL5O andl5l arefirst placed upon the verticaliflanges of the cross-bar 18 with the air passages registering as. above explained and in this position they are held positively against inovement in.all directions except directly upwardly; 'Iheblock units .40 and 41, of the next row inthe facing are then successively registered withithe ribsl4 and slipped downwardly upon the inclined face: of the bed piece 12 until they rest .uponandinterlockwiththe thinner edges of the units 50 and 51. .The block'units 40 and 41 ofrtheinext row are similarly assembled until the entire supporting face of the bed piece 12 "is covered. "Finally the hold-down member 30. is placed upon the flange of the cross-bar 26 and it will be seen thatits lower face rests directly upon the flat inclinedff'aces'42 of the block. units 40 and i l-of the uppermost row. The whole assembly is thus .lockedzreliably and securely in place upon th'ecgrate without the use of threaded fastenings.

of anyrkind or of any fastening device except th'eh-old-Ldown member 30 which is of plane, flatfacediconstruction and not likely to become distortedmnderthe temperature conditions to which F it is subjected.

'li'heholddown member 30 is positioned upon the cross-bar 26 by a combined sliding and rotating movement. The rib 83 of this member is relatively shallow and rounded while the rib is provided with a rounded rearwardly extending foot, as best shown in Fig. 5. The under surface of the cross-bar 26 is curved or beveled so as to permit this foot to swing beneath it in positioning the hold-down member. It will be seen that when the latter is thus located in operative position, it cannot be displaced by direct upward pressure but must be released by a combined lifting and rotary movement.

For the purposes of replacement the facing may be disassembled by following a reverse procedure.

It will be apparent from the foregoing descrip-v tion that I have produced a protected grate structure of long life and high efficiency both mechanically and thermally, comprising an assembly of 1 simple mechanical parts which' may beinanufactured conveniently and at? low cost. The design of the refractory blockunits particularly favors manufacture economically and withsmall wastedue tobreakage. I i l N Having thus described niyinvention, what I claim as newand desire to secure by Letters Paterit of the United States is z 1. A'grate for furnaces, comprising ametallic frame having'an inclinedsuppor-ting face, an upper facing of refractory block unitsarranged in tory block units assembled upon thesupporting face of said frame, successively ove apping each other'in rows and one row overlapping" said anchored units, and interlocking means carried by the frame and units and acting to prevent move ment of the units awayfroin the frame without preventing movement thereof down said inclined face. i I

'3. A grate for furnaces, comprising a frame having an inclinedsuppcrting face With-longitudinal ribs thereon, and a transverse flange with stops adjacent thereto near the lower edge of the supporting face, and a facing of ceramic blocksassembled upon saidface in transverse rows, the lower row being anchored upon said flangeand being heldagainst transverse displacement by said stops; the blocks of each higher row overlap- .ping those'below and being-held against trans verse displacement by said ribs.

v4. A grate for furnaces, comprising a frame having an inclined supporting face with longitudinal undercut ribs thereon, transverse flanges adjacent to the top and bottom edges of the frame and the frame having air passages disposed between the longitudinal ribs, a facing of refractory block units each having an air passage therein assembled upon said supporting face and upon said lowermost flange in transverse rows with theirpassages registering with those of said face, the lowermost row being anchored upon the lowermost flangeand the units of each higher row overlapping those below it, and a removable holddown member connected to the uppermost flange and overlapping the uppermost row of block units.

5. A refractory block of ceramic material for use in facing furnace grates, comprising a body of rectangular outline having an inclined intermediate face merging into oppositely-inclined marginal faces, said body decreasing in thickness toward one longitudinal edge and having air passage grooves in an end face which open into said intermediate face.

6. A grate for furnaces, comprising a metallic frame, an inclined supporting surface and a cross bar at its upper edge, a facing of refractory blocks arranged in tiers on the frame in overlapping relation, corresponding vertical grooves fitting said flange and being thereby held against removal except in a vertical direction, and an assembled facing of ceramic blocks upon said supporting face bearing vertically upon said lower row of blocks in a manner to hold them in place upon the flange, each block being engaged with said supporting face so that it may be moved only in a direction parallel thereto.

'7. A grate for furnaces, comprising a. frame having an inclined supporting face and a flange at its lower edge, a lower row of ceramic blocks anchorediupon said flange, means for positively preventing transverse movement of the blocks along the flange, and an assembled facing of ceramic blocks slidably interlocked with the supporting face and resting upon said anchored blocks in such manner as to hold them in place upon the flange.

8. A grate for furnaces, comprising a metallic frame having an inclined supporting face with dove-tailed ribs thereon extending toward its lower. edge, a transverse flange adjacent to said lower edge, and a facing, of ceramic block units assembled in rows upon said face, the lowermost row thereof being anchored upon said flange and the units of each successive higher row being arranged to slide downwardly on the supporting face while engaged by said ribs into overlapping relation with the units of the next lower adjacent row.

9. A grate for furnaces, comprising a frame having an inclined supporting face with spaced undercut ribs and intermediate air passages, and a facing of ceramic blocks each shaped to engage the ribs and slide downwardly on said supporting face while so engaged and each individually having a part of an air passage therein, said blocks being assembled upon the supporting face with their passages registering with those of the supporting face and in interlocking relation with said ribs.

10. In a protected grate for furnaces, a frame having an inclined supporting surface and a cross bar at its upper edge, a facing of refractory blocks arranged thereon in overlapping relation in tiers, a hold-down member shaped to overlie the uppermost tier of blocks and having downwardly projecting ribs upon its lower face spaced to straddle said cross bar, one of said ribs having a laterally projecting portion adapted by a turning movement of the hold-down member to be located beneath said cross bar in interlocking relation therewith.

11. A ceramic refractory block unit adapted to be positioned upon an inclined frame in a furnace grate and comprising a body of substantially rectangular outline increasing in thickness from its upper toward its lower edge, having its thicker edge undercut to provide a covered space bounded by a concealed edge face, whereby in the grate it may overlap another block unit having a thickness equal to its own thinner edge, and havingv also an undercut groove inits bottom face dls-' posed at right angles to its lower edge.

12. A block unit as defined in claim 11, further grooves in its opposite ends which are arranged respectively in offset relation to each other, and in.

such manner that units may be assembled in adiacent relation in straight horizontal tiers on the frame with said grooves disposed in staggered relation.

14. A refractory block unit of ceramic material adapted to be secured in position upon an inclined frame in a furnace grate and comprising a body of substantially rectangular outline having in one end a groove branching upwardly into three openings through the surface of the unit and in the other end a groove branching into two openings disposed out of line with those in the end first mentioned and in such manner that the openings are staggered in adjacent units as as sembled.

- 15. A refractory block unit of ceramic materlal' adapted to be secured-in position upon aninclined frame in'a furnace grate and when so secured having a cylindrical outer face merging at its upper margin into a plane face and having grooves in both ends of the block extending radially with respect to said cylindrical face and opening through said face in locations offset at opposite ends with respect to each other and in such manner that the openingsare staggered in adjacent units as assembled.

16. A ceramic refractory block unit adapted be located on 'a downwardly-sloping frame in awhich extends at rightangles to the surface division of its upper face.

JOHN MOORE. 

